February 08, 2017
Precalc Warm Up # 8-3
Turn in extra credit
1. Find tan x given that sec x = -3/2 and tan x > 0.
Use quadrant placement and a right triangle. Then do
it again using a pythagorean identity.
2. True or false?
x
______
a+b
=
x __
x
+
a b
__
HW Questions: p. 403
a b
a+b
_____
= ___ + ___
x x
x
February 08, 2017
Fundamental Trig Identities
(True for all values of the variable in the domain.)
Reciprocal Identities
Tangent and Cotangent Identities
Pythagorean Identities
Cofunction Identities
Negative Angle Identities
February 08, 2017
The identities can be used to help solve equations and
simplify expressions. Don't overlook the power of
Algebra! It is often the best tool of all!
Simplify Examples:
1.
2. cos2x (sec2x - 1)
How could you check?
3. cos4x - sin4x
February 08, 2017
3. cos4x - sin4x
4.
5. sin b + cot b cos b
February 08, 2017
4.
5. sin b + cot b cos b
6. Rewrite so that the expression is NOT a fraction
February 08, 2017
6. Rewrite so that the expression is NOT a fraction
7. Simplify
a.
b.
February 08, 2017
7. Simplify
a.
b.
8. Use factoring to simplify
1 - 2cos2x + cos4x
February 08, 2017
8. Use factoring to simplify
1 - 2cos2x + cos4x
HW: PC book p. 403 boxed
(use identities on #3, 7, 11)